What makes some smokers different from the majority such that they do not seem to suffer from the negative effects of tobacco? It is no secret that smoking reduces one’s life span and is among the leading causes of death. How, then, do some smokers live till the age of 90, or even more? A new study attempts to explain why certain smokers can have relatively long lifespans. The findings are available in The Journals of Gerontology.

It all has to do with the DNA. When the genomes of 90 long-lived smokers (all having lived beyond 80 years of age) were compared with those of 730 smokers who died before reaching 70, it was revealed that the single nucleotide polymorphism (SNP) sequences of DNA of certain people confer on them some kind of protection from the damage caused by long-term smoking.

“We identified a set of genetic markers that together seem to promote longevity,” said author Morgan E. Levine in a statement. “What’s more, many of these markers are in pathways that were discovered to be important for ageing and lifespan in animal models.”

The researchers spotted a series of SNPs in genes responsible for anti-ageing effects such that the individuals bearing them had a 22 % increase in the probability of reaching till 90-99 years of age; these people are also three times more likely to reach 100 years of age. Furthermore, these genes are linked with an 11 % lower cancer prevalence.

“There is evidence that these genes may facilitate lifespan extension by increasing cellular maintenance and repair,” said Levine. “Therefore, even though some individuals are exposed to high levels of biological stressors, like those found in cigarette smoke, their bodies may be better set up to cope with and repair the damage.”

The researchers write that this type of smokers might form a “biologically distinct group, endowed with genetic variants allowing them to respond differentially to environmental stressors”.

Levine also cautioned people not to use the findings to justify continuing smoking.

“[The proportion] of people who have a ‘genetic signature’ that would help them cope with the biological stresses of smoking is extremely small, and therefore, nobody should use this paper as an excuse to continue smoking,” he said.